// 字符串加数字 数字就会转换成字符串 数字加数字或者字符串加字符串
var res1 = 1 + 2 + 3 + '4'
console.log(res1, typeof res1);
var res2 = '100' - '50'
console.log(res2, typeof res2);

// == 隐式转换
console.log(1 == true);
console.log(0 == false);